Optimization Design Of Short Block And Low Rate Channel Coding

When transmitting information in control channels where there may be strong interference,traditionally spread spectrum technology may be used to resist strong interference.However,spread spectrum technology can only gain processing gain and can not gain coding gain.The low rate coding can gain processing gain,compared with spread spectrum coding technology,the low rate coding can improve the channel coding gain.The Turbo-Hadamard code proposed by Li Ping et al.has the outstanding performance and approaching the channel capacity based on a very long code length.When the code length is very long,the real-time communication can not be guaranteed.Therefore,this paper mainly studies the optimal design of short block Turbo-Hadamard codes.The paper first analyzes the structure of Turbo-Hadamard codec and its related decoding algorithm.Then the emphasis is put on the performance analysis of Turbo-Hadamard codes with short block.The main work is as follows:1.The impact of various factors on the performance of Turbo-Hadamard codes with short block is analyzed;2.The performance comparison of Turbo-Hadamard codes with short block and other low bit rate codes is carried out;3.The weight spectrum characteristics and decoding performance of Turbo-Hadamard codes are analyzed,and the factors that affect the decoding performance of Turbo-Hadamard codes are analyzed.In addition,The Turbo-Hadamard code factor graph is proposed,and the importance of the interleaver design to the performance improvement of the Turbo-Hadamard code is verified by the factor graph theory.Then base on the factor graph of Turbo-Hadamard code,a parallel coprime interleaver and parallel QPP interleaver design algorithm are proposed.The simulation results show that the structure of Turbo-Hadamard codec uses the parallel coprime interleaver proposed in the paper,and the parallel QPP interleaver has better performance than the random interleaver.At the same time,in the design of parallel QPP interleaver,the parameter search space of a single QPP interleaver is optimized according to the related properties of QPP interleaver,which speeds up the process of searching a single QPP parameter.